The ever increasing consumer expectations regarding multi-media delivered to households place significant burden on the equipment and infrastructure providing these services. In some cases, such as cable systems, heavy up-front costs incur for laying cable in residential neighborhoods, while in other cases, such as terrestrial digital television (DTV) broadcasts, cost-effective equipment that can reliably provide indoor reception remains more of a promise than a product.
Such barriers to entry have forced businesses to seek alternative methods of delivering rich multi-media content to the households. For example, to provide broadband internet access, Digital Subscriber Loop (DSL) technology uses multi-carrier modulation of digital data over decades old twisted-pair copper wires that have existed for telephony services. Broadband connectivity through existing copper networks that are not designed for such data-rates, while providing an advantage over cable, has slowed down the anticipated roll-out of DSL (digital subscriber loop) and, thus, many neighborhoods in the U.S. are connected by broadband cable.
The terrestrial television broadcast provides an existing infrastructure capable of reaching hundreds of millions of consumers, though, by nature, it is a one-way communication system. The lack of a return communication link (i.e. from consumer to central office) severely limits the utility of this broadcast system, despite the appeal that no wires or cables need to be installed. Datacasting is a technique that broadcasts ancillary data together with a television signal, but, despite its appeal, has been largely unsuccessful in the past. In 2003, however, the Walt Disney Corporation launched a video-on-demand service called MovieBeam using datacasting techniques, and to date, it is the largest and most successful datacasting effort over analog television.
The MovieBeam technology inserts a data-bearing subcarrier, which is in quadrature to the video carrier, into the video signal. By maintaining quadrature to the video carrier, impairment of the analog television signal is kept to an imperceptible level, allowing normal television reception. It also facilitates the reception of the digital data with a special receiver set-top-box. These data insertion and extraction techniques are described in the U.S. Pat. No. 6,433,835, titled “Expanded Information Capacity For Existing Communication Systems,” issued to Ted Hartson et al., and the U.S. patent application Ser. No. 10,246,084, titled “Adaptive Expanded Information Capacity For Communication Systems,” by Chris Long et al., filed Sep. 18, 2002.